1. Field of Invention
The present invention relates to an adapter. More particularly, the present invention relates that act as a link between an earphone-microphone and a mobile telephone.
2. Description of Related Art
As wireless communication continues to develop and semiconductor fabrication techniques continue to improve, mobile telephones are becoming more lightweight, compact and multi-functional. In fact, the mobile telephone has become a piece of indispensable communication equipment in our daily lives. However, in some situations, holding a mobile telephone with a hand is inconvenient or even dangerous. For example, using a hand to reach for a mobile telephone while driving a car can be quite hazardous. Therefore, most mobile telephones have a socket for connecting to an external earphone-microphone set.
FIG. 1A is a schematic drawing of a conventional earphone-microphone set and a mobile telephone. FIG. 1B is a circuit diagram showing the electrical connection within the earphone-microphone set as shown in FIG. 1A.
As shown in FIGS. 1A and 1B, the earphone-microphone set 100 comprises an earphone 120, a microphone 130 and a plug 110. The plug is a plug containing three terminals 111, 112 and 113. One end of the microphone 130 is connected to the terminal 111 of plug 110, while the other end of the microphone 130 is connected to the terminal 112 of plug 110. The plug 110 is made to fit into the socket 13 of a mobile telephone 10. The socket 13 has internal contacting points (not shown in the Fig.) for connecting with the three corresponding terminals of the plug 110. Therefore, when the plug 110 is plugged into the socket 13, the earphone 120 and microphone 130 are connected to the internal circuit of the mobile telephone 10.
When the earphone-microphone set needs to be used, the user can put the earphone 120 onto one's ear. The microphone 130 is specially positioned so that it is close to the user's mouth when the earphone is plugged into the ear. Hence, the user can use the mobile phone without having to hold it with a hand.
Although the aforementioned conventional earphone-microphone set 100 can provide mobile telephone user with much convenience and safety, the mobile telephone is usually placed somewhere out of sight. For example, most users wear their mobile telephone around their waists. Hence, when there is an incoming call, the user has to grope for the buttons on the telephone panel, and press the correct button before being able to receive the call. This method of receiving calls causes great inconveniences, especially when the user is driving a car, because a user must divert his or her gaze to look for the mobile phone. Consequently, mobile telephone manufacturers have decided to add new functions to the conventional earphone-microphone set.
FIG. 2A is a sketch of a newer version of conventional earphone-microphone set and a mobile telephone. FIG. 2B is a circuit diagram showing electrical connection within the earphone-microphone set as shown in FIG. 2A.
As shown in FIGS. 2A and 2B, the microphone 200 similarly has an earphone 220, a microphone 230 and a plug 210. However, an additional call-receiving switch 240 is also installed at a convenient location for picking up incoming calls so that a four-terminal plug 210 is used. The plug 210 has four terminals including 211, 212, 213 and 214. Connection of the terminals to the earphone and microphone is very similar to the aforementioned earphone-microphone set 100 in FIGS. 1A and 1B.
In other words, the two ends of the microphone 230 are connected to the terminals 211 and 213 of the plug 210, respectively. The two ends of the earphone 220 are connected to terminal 212 and terminal 213 of the plug 210, respectively. The two ends of the call-receiving switch 240 are connected to the terminal 213 and the extra terminal 214 of the plug 210, respectively. The plug 210 can be plugged into the socket 23 of a mobile telephone 20. After the plug 210 is plugged into the socket 23, the four terminals of the plug 210 are connected to the corresponding internal contacting points (not shown) within the mobile telephone 20.
Hence, the earphone 220 and the microphone 230 are both connected to the internal circuit of the telephone 20. The mobile telephone 20 has special circuit for detecting any change of state in the switch 240 connected in parallel between terminals 213 and 214. If the user flips the switch 240 from open to close position, this reflects the user's needs to pick up an incoming call.
Although the second conventional earphone-microphone set 200 is able to pick up incoming calls with ease, the set 200 still does not have a muting function. Therefore, some inconvenience still exists in operation. For example, when a user is communicating with a second person at the other end of a mobile telephone, and if the user also wants to discuss private or confidential matters with a third person nearby and does not want their conversation to be overheard by the second person, the user has to take the earphone-microphone set off the ear and leave it in a far away place.
When the user has finished discussion with the third party, the user has to fetch the earphone-microphone set and put it back on. Moreover, even if the earphone-microphone set is far away from the user, the highly sensitive microphone can still pick up some signals and broadcast to the other side of the mobile telephone. Furthermore, the older type of earphone-microphone set cannot be re-used. If the new call-receiving function on the earphone-microphone set is required, one has to purchase the entire earphone-microphone set. Consequently, not only is money wasted, but the old earphone-microphone sets are also wasted, too.
Hence, in summary, the two types of conventional earphone-microphone sets have the following drawbacks:
1. Without a muting function, using the mobile telephone is inconvenient. It is difficult to prevent the other party on the other side of the mobile telephone to overhear private conversation. PA1 2. Newer functions cannot be added to the old earphone-microphone set. Consequently, a complete earphone-microphone set must to be purchased, and the old earphone-microphone set has to be thrown away. This is a waste of the user's money and resources.
In light of the foregoing, there is a need to provide an adapter for improving the earphone-microphone set operation.